In an advance, online publication of Science this week, Chaolin Zhang and colleagues at The Rockefeller University report their approach for "understanding mammalian RNA regulation at the systems level" using "Bayesian networks to probabilistically model diverse datasets and predict the target networks of specific regulators." Zhang et al. used their strategy to elucidate nearly 700 alternative splicing events that are directly regulated by Nova, a neuron-specific factor in the mouse brain.
In this week's issue of Science, researchers at the University of Massachusetts Medical School and Boston University show that there is "extensive complementarity between a target RNA and an Argonaute1-bound miRNA triggers miRNA tailing and 3'-to-5' trimming" in Drosophila. Argonaute2-bound small RNAs bear a 2'-O-methyl group at their 3' ends in the fly, which "blocks target-directed small RNA remodeling," the authors write, adding that their results suggest "an explanation for the partial complementarity between animal miRNAs and their targets."
A trio of researchers at the Yale University School of Medicine report the "down-regulation of a host microRNA by a Herpesvirus saimiri non-coding RNA" in Science this week. Demián Cazalla and colleagues show that miR-27 is "dramatically lowered" in virally transformed T cells, and that the "transient knockdown and expression of HSUR1 demonstrate[s] that it directs degradation of mature miR-27 in a sequence-specific and binding-dependent manner." The authors conclude that this viral strategy depicts how ncRNAs manipulate host-cell gene expression using the miRNA pathway.
And in a perspectives piece, "Paring miRNAs through pairing," Amy Pasquinelli at the University of California, San Diego speaks about miRNAs and their targets. In referencing the Cazalla paper, Pasquinelli writes that "the ability of HSUR1 to bind and destabilize miR-27 illustrates how the presence of a viral transcript can disrupt the expression of multiple endogenous genes normally regulated by this miRNA." She suggests that knowledge of the base-pairing between siRNA and target RNAs can "can reduce the half-life of the siRNA should guide the design of RNA[i] tools with greater potency in vivo."